| My gym does the classic rock stuff too and I frequently roll my eyes to the selection. Its irritating when I forget my own music and have to put up with it, especially on low traffic days when you can hear it better over the whir of the machines. I have to laugh when I'm lifting in the same room with guys 3x my size and they're straining and grunting to some Faith Hill song-I mean, how motivating can that be?
I get that everyone has different tastes and classic rock is probably the most "safe" across all generations. Every once in a while some more contemporary stuff will get mixed in, which is great. I too have songs I hear elsewhere that remind me of the gym because they are strickly "gym songs" thats when you know you're there too much :P | 
